Ceramic bodies having cellular (e.g., honeycomb) structures are used to form particulate filters for a variety of filter-based applications, such as vehicular exhaust systems, to reduce pollutants. Such structures generally comprise a network of interconnected web walls that form a matrix of elongated, gas-conducting cells that may have, for example, a square, octagonal or hexagonal cross-sectional shape. A cylindrical outer skin that is integrally connected to the outer edges of the web walls surrounds the network of web walls such that a round-shaped or an oval-shaped cross-sectional structure is formed having opposing inlet and outlet ends for receiving and expelling exhaust gases through the matrix of cells.
It is useful to be able to measure and characterize various properties of ceramic bodies without damaging or destroying the cellular ceramic body. Such measurement and characterization assist in determining whether there are faults (e.g., cracks or fractures, deformities, density variations, etc.) and whether the product conforms to the design specifications. Generally, such measurements provide insight into the manufacturing process and can be used to improve the process. It would be particularly useful to measure and characterize various properties of the ceramic bodies during thermal processing, such as scintering or thermal shock testing, where the ceramic body is not readily accessible to measurement.
One particularly useful property of a ceramic body is its “specific modulus,” which is a measure of an object's ability to be non-permanently deformed and can be considered an indicator of the object's resistance to breakage. The specific modulus of a material is essentially the elastic (Young's) modulus divided by the material's density. This parameter is useful in comparing different materials in designing the ceramic body. The specific modulus of an object can be determined by measuring the strain placed on the object in response to an applied stress, normalized by the object's density. The specific modulus of a ceramic body yields information about its composition, its brittleness, etc. The measured specific modulus can also be compared to a specified value to assess whether a particular ceramic body, such as a diesel particulate filter (DPF) meets production specifications.